I replaced the cable to my furnace this morning. Not strictly necessary but the old cable was an armored old thing with cloth sheathing, had no ground wire, and was an eyesore snaking across my basement. I got sick of looking at it, so replaced it with a nice new piece of cable that not only doesn't snake across everything (it's tacked into place and runs through holes in the joists, rather than being very badly stapled kinda-sorta-near the joists, but also has a ground wire.
Now the 40-odd feet of armored cable I took out is sitting coiled up in a box of scrap metal, waiting for me to finish the house rewiring so I can take it all to a guy I know who gathers it for a charity he works with.